1. Field of the Invention
The present invention refers to a protective structure for vehicles.
2. Description of the Related Art
At present, the devices used on vehicles in order to limit damage during insurance or NCAP type crashes, on the front side, consist of completely metallic cross members, generally made of steel, positioned between the vehicle chassis and the bumpers; the cross member usually rests directly on and is fixed to the side members, or metal absorber devices (crash boxes), to which the cross member is connected, are fixed on the side members.
Said structures, however, do not guarantee good efficiency (understood as ratio between energy absorbed and crushing of the system) and, above all, since they have to deform to absorb energy and as they are shaped on the front strip of the bumper, the elements fixed to the side members tend to transmit high levels of stress (also in a tangential direction) on the side members thus obliging the user to adopt reinforcing devices, with consequent increase in the weight of the vehicle.
Furthermore, to adapt said structures to compliance with the requirements of the legislative proposals in the event of impact with pedestrians and, substantially, in the event of impact with the leg of the pedestrian, it is necessary to further distance them from the bumper, positioning in this space absorber elements with pressures of between 0.1 and 0.6 N/mm2, corresponding to a crushing of 50%.
Said absorber elements are generally made of foamed polypropylene, foamed polyurethane or foamed polystyrene.
In this case, however, the minimum space necessary for the installation of said absorber elements is approximately 80 mm+30 mm (the 30 mm residual space being due to densification of the material which occurs during compression of the buffer and beyond which the compression forces are very high).
In short, the above-mentioned solutions are totally unsuitable or lacking in efficiency both to satisfy the regulations concerning impact between vehicles (in particular, the so-called insurance or NCAP type crashes) and to meet the requirements relating to pedestrian impact; furthermore, it is to be hoped that further additional systems will be provided in front of the bumper able to absorb energy during the impact, without requiring too much space between cross member and bumper.